Unusual Skill
Adds one skill of your choice to your class skills list.
It's my first homebrew rule. Mostly so one of my players can be a sorceror instead of a wizard and still reach the PrC he wants to use with less than ten levels.
(I'm a new DM and learning all the wizard rules was not yet feasible, working on that now.)
But it seemed a fair trade to me. This probably already exists and I just didn't know of it.